2.1. Participants

This study was performed according to the Declaration of Helsinki and approved by the institutional review boards of Nanjing Drum Tower Hospital. Written informed consent was obtained from all participants before they were included. 60 participants in total (67.7 ± 11.2 years; range, 40 to 87 years) were recruited from May 2015 to January 2016, including MCI patients (n = 33, 68 ± 13 years old) and NC (n = 27, 65 ± 12 years old). All were right-handed and underwent a series of standardized clinical assessments including neuropsychological, neurological, and psychiatric evaluations. Participants would be excluded if they had a positive history of major neurological or psychiatric disorder other than AD/MCI, drug, or alcohol abuse and intracranial findings that might contribute to cognitive impairment (e.g., cortical infarcts, hydrocephalus).